1.55 μm wavelength region high-stability optical fibre lossvariation measurement using fibre coupler

A 1.55 μm-wavelength high-stability optical fibre loss variation measurement system, using a comparison method with an optical fibre coupler, was developed. Long-term stability within ±0.001 dB over a 120 hour period at a room temperature variation of ±2.2°C has been achieved     

Low-noise single-photon detection at wavelength 1.55 μm

The photon-counting performance of commercially available InGaAs/InP avalanche photodiodes operated in Geiger mode was investigated at temperatures between 77 and 260 K. In particular, their noise equivalent power was measured to be 4×10^-17 WHz ^-1/2 at 77 K. The implications of these results in the context of a quantum cryptography application are discussed     

Multi-wavelength, continuous wave fibre Raman ring laser operatingat 1.55 μm

A four wavelength continuous wave, fibre Raman ring laser has been demonstrated at room temperature using fibre Bragg gratings as the wavelength-selective elements with applications as a multi-wavelength source for optical fibre telecommunications. Channel spacings were ~5 nm between 1551.6 and 1565.1 nm with 14.9 dBm total output power     

1-mW CW-RT monolithic VCSEL at 1.55 μm

In this letter, we demonstrate the first result of a high-power (1 mW) continuous-wave room-temperature vertical-cavity surface-emitting laser emitting at 1.55 μm using a single InP substrate. The whole structure was grown monolithically using gas source molecular beam epitaxy and incorporates two original approaches. The first originality consists in the growth of a metamorphic GaAs-AlAs Bragg mirror directly on an InP-based cavity. The second novel idea is to use a tunnel junction for current injection. Moreover by using these two approaches the processing is very simple and, therefore, fulfills the goal for low-cost laser production in access and interconnections applications     

Deep sea trial of 1.55 μm optical fibre submarine cable system

The first 6000 m deep sea trial of a 1.55 μm optical fibre submarine cable system was successfully conducted in the Pacific Ocean, near Torishima Island, in January 1988. By using 1.55 μm loss-minimised single-mode fibre cables and submerged fully monolithic Si-IC regenerators with DFB lasers, excellent transmission performances at 140, 280 and 565 Mbit/s were obtained through 150 km repeater spacings, respectively     

Chromatic dispersion measurement in 1.55 μm narrow-band regionusing a tunable external-cavity laser

Measurement of the chromatic dispersion of an 80.6-km-long, concatenated, dispersion-shifted, single-mode fiber (DSF) with a tunable 1.55-μm external-cavity laser diode, using the phase-shift technique at 1.55 μm over 80-nm bandwidth, is discussed. It is shown that the technique does not need intricate curve-fitting equations or a large number of laser sources with specified wavelengths. As a result, the measurement configuration and procedure are relatively simple. The technique is useful for measuring the chromatic dispersion of future advanced fibers such as dispersion flattened fibers with various refractive index profiles     

Neodymium-doped fibre amplifier at 1.064 μm

For the first time, a fibre amplifier with a small signal gain of more than 30 dB at 1.064 μm has been realised. The amplifier employs an Nd-Al codoped fibre and a 0.808 μm pumping laser diode which offers 50 mW incident pump power     

Efficient high power operation of erbium 3 μm fibre laserdiode-pumped at 975 nm

Efficient CW operation of a 2.71 μm Er,Pr:ZBLAN double-clad fibre laser pumped with a single diode laser operating at a wavelength of 975 nm is described. A maximum output power of 0.5 W and a slope efficiency of 25% (with respect to the launched pump power) were obtained. Threshold pump powers of <200 mW launched were measured and consistent relaxation oscillations in the output from the fibre laser indicate the presence of a saturable absorption mechanism     

A single-polarization optical fiber of hollow pit type with zerototal dispersion at wavelength of 1.55 μm

This paper gives a design method for the single-polarization optical fiber which satisfies simultaneously the wide single-polarization bandwidth, the large modal birefringence, and the zero total dispersion at the wavelength of 1.55 μm. As a type of single-polarization fiber, the optical fiber with two hollow circular pits across the core-clad interface is proposed and designed. The normalized power (=Δ the power in the core/the total power) in the core is also evaluated for the designed fibers. It was found from the numerical analysis that when the zero total dispersion is satisfied at the wavelength of 1.55 μm, the maximum modal birefringence of 1.133×10^-3 and the maximum single-polarization bandwidth of 100.6 nm are attained for the relative index difference of 1.6%. Then the normalized power in the core is 0.859     

Predistortion of electroabsorption modulators for analog CATVsystems at 1.55 μm

A predistortion circuit with adjustable amounts of third- and fifth-order predistortion is studied both theoretically and experimentally. The circuit is used to cancel the third- and fifth-order intermodulation distortion of a 1.55-μm integrated electroabsorption modulator/DFB laser. The CSO obtained is -61 dBc and the CTB is reduced 22.6 dB to -65 dBc. This performance is maintained after fiber amplification and propagation through 13 km of nondispersion shifted fiber due to the modulator's low chirp. Dithering of the DFB laser's injection current is employed to increase the stimulated Brillouin scattering (SBS) threshold to +13.4 dBm     

Threshold currents of 1.2-1.55 μm P-substrate buried crescentlaser diodes

P-substrate buried crescent (PCB) laser diodes whose wavelength ranged from 1.2 to 1.55 μm have been fabricated. The threshold currents as low as 10 mA have been obtained in this wavelength range experimentally. The calculated threshold currents of 13, 13, and 14 mA at 1.2, 1.3, and 1.55 μm almost coincide with the measured values     

Dual mirror and resonant cavity operating at 1.3 and 1.55 μm

A GaAs/AlAs Bragg mirror with two reflectivity bands centred at 1.3 and 1.55 μm is reported. High reflectivity is achieved in both bands and good agreement is observed between measured and simulated reflectivities. A microcavity structure is proposed that is resonant at both wavelengths. Such structures can be used to enhance the absorption or emission of signals at the two wavelengths     

Wavelength conversions between the two silica fibre loss windows at1.31 and 1.55 μm using difference frequency generation

Wavelength conversions between the two silica fibre loss windows at 1.55 and 1.31 μm have been demonstrated, for the first time, using difference frequency generation (DFG) in a periodically domain-inverted LiNbO₃ channel waveguide. The conversion efficiency, which is proportional to pump light power, is -31 dB for a pump light power of only 3.6 mW     

4×4 polymer thermo-optic directional coupler switch at 1.55μm

An integrated 4×4 polymer thermo-optic switch at 1.55 μm is demonstrated for the first time. A fibre to fibre insertion loss of 10 dB, and extinction ratios of 17.5-19.5 dB were measured. The polarisation sensitivity was typically less then 0.5 dB and the response time was less then 1 ms. The electrical power consumption was found to be 70 mW per single switch     

Low-loss quadruple-clad single-mode lightguides with dispersion below 2 ps/km nm over the 1.28 ?m?1.65 ?m wavelength range

Low-loss fibres with dispersion below 2 ps/km nm over the spectral range between 1.28 ?m and 1.65 ?m have been designed and fabricated. These fibres were achieved by the use of quadruple cladding and designed with the use of a computer analysis program. They should be desirable for future wavelength-division-multiplexing applications.     

A 3 GHz transimpedance OEIC receiver for 1.3-1.55 μm fiber-opticsystems

A high-performance metal-semiconductor-metal high-electron-mobility transistor (MSM-HEMT) transimpedance photoreceiver fabricated using OMCVD-grown InAlAs/InGaAs heterostructures on an InP substrate is discussed. This is the first demonstration of a monolithically integrated receiver amplifier that incorporates a cascode amplifier stage and a Schottky diode level-shifting stage implemented on InP-based optoelectronic integrated circuit (OEIC) photoreceivers. The transimpedance amplifier has an open-loop gain of 5.7 and a bandwidth of 3.0 GHz, which represent the highest gain and the highest speed performance reported for 1.3-1.55-μm-wavelength OEIC receivers     

Continuous wave lasing at 2.7 μm in an erbium-dopedfluorozirconate fibre

A fibre laser operating at 2.702 μm using fluorozirconate fibre doped with <0.1 mol.% of erbium is reported. The authors propose that the mechanism which allows CW operation is absorption of pump radiation by ions in the lower lasing level     

Intersubband transitions at 1.3 and 1.55 μm in a novel coupledInGaAs-AlAsSb double-quantum-well structure

We report the first observation of intersubband absorption at 1.3 μm in a coupled InGaAs-AlAsSb double-quantum-well structure lattice matched to InP substrate. The novel structure exhibits intersubband transitions concurrently at 1.3 and 1.55 μm due to the strong coupling of the intersubband states of the adjacent wells. A transient analysis of optical response in the multilevel conduction subband states for the designed structure indicates ultrafast optical switching behavior with a subpicosecond response     

1.55 μm, 2.5 Gb/s direct detection repeaterless transmission of160 km nondispersion shifted fiber

A repeaterless transmission experiment through 160 km of non-dispersion-shifted fiber at bit rate of 2.5 Gb/s is reported. A direct-current-modulated distributed-feedback laser in conjunction with an erbium-doped fiber amplifier for power amplification constitute the transmitter. The regenerator includes the conventional APD photodetector and the subsequent amplifiers and timing recovery circuit. With careful decision level and laser bias adjustment, less than 0.6 dB of overall system degradation is incurred in this simple system configuration     

Lasing at 2·08 μm and 1·38 μm in a holmiumdoped fluoro-zirconate fibre laser

The authors report for the first time a fibre laser operating beyond the 1·55 μm communications window. Using a holmium doped fluoro-zirconate fibre, laser emission occurs from the three-level 2·08 μm transition, and also at 1·38 μm via a cascading transition